Identification of amino acid residues involved in the interaction of canine IgE with canine and human FcERII

• Published in: Molecular immunology Vol. 57; no. 2; pp. 111 - 118
• Main Authors: Ye, Hongtu, Housden, Jonathan, Hunter, Michael, Sabban, Sari, Helm, Birgit
• Format: Journal Article
• Language: English
• Published: 01-02-2014
• Subjects: Pichia pastoris
• ISSN: 0161-5890
• DOI: 10.1016/j.molimm.2013.08.013

The interaction of immunoglobulin E (IgE) antibodies with the high-affinity receptor (FcERI) is important in anti-parasitic immunity and plays a central role in allergic responses. It has been shown that the human CE3 domains comprise the binding sites for FcERII- and crystal structure determination has shown that amino acids in four sites contribute to the high affinity of the interaction. The role of homologous residues within canine IgE-Fc, i.e. amino acids located at CE2aCE3 interface (residues 332a337), loop BC (residues 362a365), loop DE (residues 393a396), and loop FG (residues 424a427) in canine CE3 domain were targeted by site-specific mutagenesis. The functional consequences of the mutations to support (i) IgE-mediated, antigen-induced release of I2-hexosaminidase from RBL cells transfected with canine or human FcERII- and (ii) the affinity of the mutants for the soluble extracellular domain of the I--chain expressed in Pichia pastoris were determined by Surface Plasmon Resonance (SPR). Kinetic analysis supports the observed effects of IgE mutations on stimulus secretion coupling. Potential applications of this study, leading to the generation of an IgE variant with a disabled FcERII- binding site, are discussed.